Guozhi Fan,Chongjing Liao,Tao Fang,Shanshan Luo,Guangsen Song
The acetylation of cellulose using sulfonated Amberlyst 15 as a new and reusable catalyst was investigated. Optimization of the acetylation process was carried out by variation in the amount of added catalyst, acetic acid, and acetic anhydride as well as the reaction conditions, which includes reaction time and reaction medium. Cellulose acetate, with a degree of substitution (DS) value of 2.38 and yield of 54.1%, was obtained under the optimized conditions and characterized using Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis–derivative thermogravimetry (TGA–DTG), and differential scanning calorimetry (DSC). The sulfonated polymer catalyst could be easily recovered by centrifugation after acetylation. Both the fresh and recovered catalysts were characterized by means of FTIR, TGA–DTG, DSC, and scanning electron microscopy (SEM), and the recovered catalyst could be successfully reused without further treatment. It was found that Amberlyst 15 possessed excellent catalytic stability, no significant changes in the DS values, and consistent yields of cellulose acetate observed over four reaction cycles.
Fang Xie,Xiaoqing Liu,Nian Liu,Xiaofang Feng,Zhijun He,Zia-ud Din,Shuiyuan Cheng,Yangchao Luo,Jie Cai
To develop a promising selenium supplement that overcomes the instability and poor water dispersibility of selenium nanoparticles (SeNPs), we synthesized a series of amphiphilic octenyl succinic anhydride starch (OSAS) through esterification. As the degree of substitution ( DS ) increased, the particle size of OSAS micelles and the critical micelle concentration (CMC) decreased. FTIR and XRD analysis confirmed the successful introduction of octenyl succinic anhydride groups onto starch. Subsequently, OSAS micelles were used as carriers to synthesize SeNPs via in situ chemical reduction, forming SeNPs-loaded self-assembled starch nano-micelles (OSAS-SeNPs). The OSAS-SeNPs exhibited spherical dispersion in water with an average diameter of 116.1 ± 2.3 nm, contributed to enhanced hydrophobic interactions. TEM images showed a core-shell structure with SeNPs as the core and OSAS as the shell. FTIR results indicated hydrogen bonding interactions between OSAS and SeNPs. Due to the negatively charged OSAS shell and hydrogen bonding (O H⋯Se), OSAS-SeNPs remained non-aggregated for one month at room temperature, demonstrating remarkable stability. This study suggests that using OSAS can address the synthesis and stability issues of SeNPs, making it a potential selenium supplement candidate for further evaluation as an anticancer agent.
In this work, bacterial cellulose (BC) was activated by ethylenediamine (EDA) and then dissolved in lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) aqueous solutions. The resulting transparent solution was cast on a glass plate to prepare regenerated BC. Then cationic BC was prepared homogeneously by the reaction between regenerated BC and 3-chloro-2-hydroxypropyl-trimethyl ammonium chloride (CHPTAC) in a NaOH/urea aqueous solution. Structure and properties of the BC and its products were characterized by different techniques such as X-ray diffraction (XRD), Fourier transform spectroscopy (FT-IR), scanning electron microscopy (SEM) and thermo-gravimetric analysis (TGA). The results showed that there was no significant difference between the structures of BC, activated BC and regenerated BC. The effects of different temperature and molar ratio of CHPTAC to anhydroglucose unit (AGU) on the degree of substitution (DS) value were examined. The DS values of cationic BC ranged between 0.21 and 0.51.
危险品化学品经营许可证（带存储）